Control of fertility in male rats by subcutaneously implanted silastic capsules containing testosterone

One or two silastic capsules filled with approximately 12 mg of testosterone were implanted subcutaneously in adult male rats. The animals were autopsied one to two months after implantation of the capsules. Mating behaviour, fertility, biochemistry of the accessory reproductive organs and testicular histology were studied. In rats with one implant of testosterone for one or two months and with two implants of testosterone for one month, the epididymal sperms were motile and after successful matings, the females littered normally. In rats bearing two silastic capsules for two months, spermatogenesis was inhibited at the spermatocyte stage and the epididymal smears were devoid of sperms; Leydig cells were atrophic and matings were infertile. Testicular histology, motility of epididymal sperms and fertility were restored to normalcy one month after removal of the capsules. In all treated groups, weights of the accessory reproductive organs and the fructose content of coagulating glands were more than those of controls. This study suggests that low doses of testosterone released through silastic capsules can be used for control of fertility in males